1. Field of the Invention
The present invention relates to an information recording method, a format changing method, and an information reproduction method; and more specifically to a method for recording video information or audio information on a recording medium, a method for changing the format of the video information or audio information recorded on the recording medium, and a method for reproducing the video information or audio information recorded on the recording medium.
2. Description of the Background Art
Recently, recordable DVDs (Digital Versatile Discs), including rewritable DVDs such as DVD-RW discs and DVD-RAM discs which are phase change optical discs having a capacity of several gigabytes and write once read many DVDs such as DVD-R discs, have been developed. Also, MPEG (Moving Picture Image Coding Experts Group) 2, which is a coding standard for digital AV (audio/video) data, has been put into practice. The development of the recordable DVDs and MPEG2 has made it possible to handle large capacity data such as video data in the state of being recorded on optical discs which are superb in access speed.
In order to fully utilize the accessibility of the optical discs, recordable DVDs have management information recorded thereon for managing where on the disc certain data is recorded, unlike tape mediums. For regulating the management information, the DVD Specifications for Rewritable/Re-recordable Discs (DVD Video Recording format; hereinafter, referred to as the “DVD-VR format”) have been issued. Also, the DVD Specifications for Read-Only Discs (DVD Video format; hereinafter, referred to as the “DVD-Video format”), which are set for mediums which can be only reproduced, are used as a recording format. In the following description, descriptors, pointers and the like which are recorded in volume structures and file structures of DVD mediums have a data structure defined in the ISO/IEC 13346 Standards or the UDF (Universal Disc Format) Standards, unless otherwise specified.
As described above, there are two different recording formats, i.e., the DVD-VR format and the DVD Video format, for DVD-RW discs and DVD-R discs. Although the details will be described later, the logical structure of the DVD-VR format (FIG. 12) is different from the logical structure of the DVD-Video format (FIG. 17). The file system of the DVD-VR format (FIG. 13) is also different from the file system of the DVD-Video format (FIG. 18). (A “file system” is a system used for managing data in a disc as directories or files). In addition, the recording format of AV data and management data of the DVD-VR format (FIG. 14 through FIG. 16) is different from the recording format of AV data and management data of the DVD-Video format (FIG. 19 and FIG. 20).
Due to the existence of these different recording formats, a method for changing the format has conventionally been demanded. An exemplary conventional technology especially related to the present invention is described in Japanese Laid-Open Patent Publication No. 2003-101927. This patent document describes an apparatus for converting stream data of the DVD-VR format into stream data of the DVD-Video format.
Hereinafter, with reference to FIG. 12 through FIG. 20, the DVD-VR format and the DVD-Video format will be described in detail. First, a data structure of the DVD-VR format will be described. FIG. 12 shows a physical data structure managed by the physical sector address of the DVD-VR format and a logical data structure managed by the file system of the DVD-VR format.
In FIG. 12, a recordable DVD 1200 is a DVD medium having data of a program recorded thereon in accordance with the DVD-VR format. A lead-in area 1201 has, for example, a reference signal necessary for stabilizing servo and a medium identification signal recorded therein. A volume structure area 1202 has management information for the file system recorded therein. A lead-out area 1203 has substantially the same reference signal as that in the lead-in area 1201 recorded therein. The lead-in area 1201 is recorded at the beginning of the physical sector address, and the lead-out area 1203 is recorded at the end of the physical sector address. A user data area is provided between the lead-in area 1201 and the lead-out area 1203. In the user data area, logically valid data is recorded. At the beginning of the user data area, the volume structure area 1202 is recorded.
The data recorded in the user data area has a file structure as shown in FIG. 12. More specifically, the data recorded in the user data area is recorded in a DVD_RTAV directory 1205 below a ROOT directory 1204. The data recorded in the DVD_RTAV directory 1205 is recorded as a plurality of files. These files are roughly classified into two types. One is a management information file, and the other is AV files. The AV files are further classified into three types, i.e., a moving picture file, a still picture file, and an audio file including audio data dubbed over still pictures. As information for managing these three types of AV files, the management information file is recorded.
With the DVD-VR format, the management information file is recorded as a VR_MANGR.IFO file 1206. The moving picture file is recorded as a VR_MOVIE.VRO file 1207, the still picture file is recorded as a VR_STILL.VRO file 1208, and the audio file is recorded as a VR_AUDIO.VRO file 1209. A VR_MANGR.BUP file 1210 is a backup file having the same information as that of the management information file, i.e., the VR_MANGR.IFO file 1206, as a reserve.
With reference to FIG. 13, a data structure of the file system will be described. The data recorded in accordance with the DVD-VR format has a structure as shown in FIG. 13. More specifically, a volume 1300, which is the user data area, includes a volume structure area 1301, a file structure area 1302, a file data area 1303, and a reserved volume structure area 1304.
Recorded in the volume structure area 1301 are, for example, a volume recognition sequence 1305 having volume recognition information, a primary volume descriptor 1306 having volume attribute information, a implementation use volume descriptor 1307 having information for the processing system, a partition descriptor 1308 having partition information, a logical volume descriptor 1309 having identification information on a logical volume, an unallocated space descriptor 1310 having information on an unallocated space in the volume space, a terminating descriptor 1311 indicating the end of a basic descriptor sequence, a logical volume integrity descriptor 1312 having information on the integral state of the logical volume, and an anchor volume descriptor pointer 1313 having access start information to the volume. (It should be noted that the order and the types of data recorded in the volume structure area 1301 are not limited to the above.)
Recorded in the file structure area 1302 are, for example, a file set descriptor 1315, a terminating descriptor 1316, a space bitmap descriptor 1314 indicating the recording state of each unit such as a sector or an ECC block, a file entry including distribution information of the files of data recorded in the file data area (the start address and the data length), and a file identifier descriptor including information such as file names and attribute of the files. The file data area 1303 has the management information and the AV file described above recorded therein. The reserved volume structure area 1304 has the same data as the data recorded in the volume structure area 1301 recorded therein as a reserve.
With reference to FIG. 14, a structure of the AV data of the DVD-VR format will be described. The highest logical unit of the AV data conformed to the DVD-VR format is a Program Chain 1400 (hereinafter, referred to as the “PGC”) . The PGC designates the order of reproduction of Cells. A “Cell” is a unit of partial reproduction of the PGC. Cells are classified into a moving picture Cell which forms a moving picture zone and a still picture Cell which forms a still picture zone. A physical unit corresponding to the Cell is a Video Object (hereinafter, referred to as the “VOB”) . A moving picture VOB corresponds to a moving picture Cell, and a still picture VOB corresponds to a still picture Cell. A Cell refers to the entirety of, or a part of, the VOB.
A moving picture VOB includes a plurality of Video Object Units (hereinafter, referred to as the “VOBUs”) . A still picture VOB Group (hereinafter, referred to as the “VOG”) includes at least one still picture VOB. Management information of a moving picture VOB called “M_VOBI” is recorded in the VR_MANGR.IFO 1207, and management information of a still picture VOG called “S_VOGI” is also recorded in the VR_MANGR.IFO 1207. The moving picture VOBs and the still picture VOGs are accessed via the M_VOBI and the S_VOGI, respectively. FIG. 14 shows a PGC of the moving picture data. As shown in FIG. 14, a set of the moving picture VOBs is the moving picture file VR_MOVIE.VRO file 1207.
Next, a data structure of a VOB of the DVD-VR format will be described. FIG. 15 shows a data structure of a VOB. A VOB 1500 includes a plurality of VOBUs arranged on a time series basis. Hereinafter, a structure of a VOBU will be described using a VOBU 1501 shown in FIG. 15. The VOBU 1501 includes a sequence of 2 kilobyte packs. Packs are classified into a video pack 1503 (V_PCK) including picture data on the basis of a Group of Pictures (GOP) unit, an audio pack (A_PCK) 1504 having audio data, a sub picture pack (SP_PCK) 1505 having sub picture data, and a real time data information pack (RDI_PCK) 1502 having real time data information including reproduction time information, reproduction control information and copy control information. In general, a VOBU includes at least one V_PCK 1503 and at least one A_PCK 1504 which are multiplexed, and an RDI_PCK 1502 is multiplexed at the beginning of the VOBU.
The V_PCT 1503 includes at least one piece of picture data, the reproduction time of which is about 0.4 to 1.0 second. The RDI_PCK 1502 includes a Pack Header 1506, a System Header 1507, a Packet Header 1508, a sub stream ID (Sub_Stream_ID) 1509, and Real-Time Information Data 1510, which are conformed to the MPEG. The Real-Time Information Data 1510 includes an RDI_GI 1511 including reproduction time information, a DCI_CCI 1512 including reproduction control information and copy control information, and an MNFI 1513 including manufacturer information.
With reference to FIG. 16, a structure of the VR_MANGR. IFO, which is a management information file of the DVD-VR format, will be described. As shown in a table 1600 in FIG. 16, a VR_MANGR.IFO file 1206 is roughly divided into seven tables. Among the seven tables, an M_AVFIT 1601 includes information on the VR_MOVIE.VRO file 1207, which is a moving picture file. An M_AVFI 1602 included in the M_AVFIT 1601 includes an M_VOBI 1603, which is information on each VOB described above. The M_VOBI 1603 includes, for example, start display time information VOB_V_S_PTM 1604, an end display time information VOB_V_E_PTM 1605, and a TMAPI 1606 which is a conversion table of the display time and the recording address. The TMAPI 1606 includes, for example, a TM_ENT 1608 representing information on the entire TMAPI 1606 and a VOBU_ENT 1609 having information on the size and the reproduction time of each VOBU.
Next, the DVD-Video format, which is another recording format for DVD-R discs and DVD-RW discs in addition to the DVD-VR format, will be described. FIG. 17 shows a physical data structure managed by the physical sector address of the DVD-Video format and a logical data structure managed by the file system of the DVD-Video format. In the following, differences from the DVD-VR format will be described.
As shown in FIG. 17, with the DVD-Video format, a VIDEO_TS directory 1701 includes a video manager (hereinafter, referred to as the “VMG”) 1700 having a management information file on the entire disc, a management information file and an AV file of each video title (program) and a backup file of the management information file of each video title. The VMG 1700 includes a VIDEO_TS. IFO file 1702 having management information on the entire disc, a VIDEO_TS.VOB file 1703 which is a video object file for the menu, and a VIDEO_TS.BUP file 1704 which is a backup file of the VIDEO_TS.IFO file 1702.
The management information file of each video title has a file name represented by VTS_XX_X. IFO (X is a numerical figure). In FIG. 17, a VTS_01_0.IFO file 1705 is an example thereof. Similarly, the AV file of each video title has a file name represented by VTS_XX_X.VOB. In FIG. 17, a VTS_01_1.VOB file 1706 is an example thereof. The backup file of the management information file of each video title has a file name represented by VTS_XX_X.BUP. In FIG. 17, a VTS_01_0.BUP file 1707 is an example thereof. A DVD medium can have a maximum of 99 video titles recorded thereon and a maximum of 9 AV files for each video title.
With reference to FIG. 18, a data structure of the file system of the DVD-Video format will be described. With the DVD-Video format, unlike the DVD-VR format, file system data conformed to the ISO9660 is also recorded in addition to the data conformed to the UDF. Examples of the file system data conformed to the ISO9660 are a path table 1806 and a directory record 1807 which are recorded in an ISO9660 file structure area 1802. Such a file system structure is referred to as the “UDF bridge”. In a volume structure area 1801, data shown in FIG. 18 is recorded including a volume recognition sequence 1808. In a file structure area 1803, files shown in FIG. 18 including file identifier descriptors and file entries are recorded. In a file data area 1804, files including the management information files and the AV files described above are recorded. At the end of a volume 1800, an anchor volume descriptor pointer 1805 is recorded unlike with the DVD-VR format.
Next, a positional arrangement of the data in the file data area 1804 of the DVD-Video format will be described in detail. FIG. 19 shows a positional arrangement of the file data in the volume 1800 of the DVD-Video format. With the DVD-Video format, the VMG 1700 described above is located at the beginning of the file data area 1804, and the VMG 1700 is followed by a Video Title Set (hereinafter, referred to as the “VTS”). The VMG1700 includes Video Manager Information (hereinafter, referred to as the “VMGI”) 1900, a Video Object Set for VMG Menu (hereinafter, referred to as the “VMGM_VOBS”) 1901, and a VMGI (backup) 1902. The VMGI 1900 corresponds to the VIDEO_TS.IFO file 1702 described above. The VMGM_VOBS 1901, which is data for the title selection menu, corresponds to the VIDEO_TS.VOB file 1703, and the VMGI (backup) 1902 corresponds to the VIDEO_TS.BUP file 1704. In the VMG 1700, the VMGI 1900 is necessarily located at the beginning, and is followed by the VMGM_VOBS 1901 and the VMGI (backup) 1902 in this order. The VMGM_VOBS 1901 does not exist where there is no title selection menu.
Each VTS corresponds to a program (in FIG. 19, n number of programs are recorded). Hereinafter, a data structure of a VTS will be described using a VTS 1903. The following data included in the VTS 1903 corresponds to each data described above regarding FIG. 17. Video Title Set Information (hereinafter, referred to as the “VTSI”) 1904 corresponds to a VTS_XX_X.IFO file. A Video Object Set for Titles in a VTS (hereinafter, referred to as the “VTSTT_VOBS”) 1906 corresponds to a VTS_XX_X.VOB file. A VTSI (backup) 1907 corresponds to a VTS_XX_X.BUP file. A Video Object Set for the VTS Menu (hereinafter, referred to as the “VTSM_VOBS”) 1905 is data for the program menu, and does not exist where there is no menu. In the VTS 1903, the VTSI 1904, the VTSM_VOBS 1905, the VTSTT_VOBS 1906, and the VTSI (backup) 1907 are located necessarily in this order. As described above, one feature of the DVD-Video format is that the positional arrangement of the data is restricted. The VTSTT_VOBS 1906 is a set of VOBs referred to as a “Video Object Set” (hereinafter, referred to as the “VOBS”), and includes AV data of the VTS.
Next, a data structure of a VOBS of the DVD-Video format will be described. FIG. 20 shows a data structure of a VOBS 2000. Hereinafter, a data structure of the VOBS 2000 will be described in detail using a VOB 2001 included in the VOBS 2000. The VOB 2001 includes VOBUs 2002 on a time series basis. Each VOBU 2002 includes a sequence of 2 kilobyte packs. Packs are classified into a V_PCK 2004 including picture data on the basis of a GOP unit, an A_PCK 2005 having audio data, a SP_PCK 2006 having sub picture data, and a navigation pack (NV_PCK) 2003 including reproduction time information and data search information.
In each VOBU, the NV_PCK 2003 located at the beginning, the V_PCK 2004, the A_PCK 2005 and the SP_PCK 2006 are multiplexed. The NV_PCK 2003 includes a Pack Header 2007 and a System Header 2008 which are conformed to the MPEG, and a PCI_PKT 2009 having reproduction control information and a DSI_PKT 2010 having data search information.
As described above, there are two different recording formats, i.e., the DVD-VR format and the DVD-Video format, for DVD-RW discs and DVD-R discs. Therefore, for example, for additionally recording AV data in accordance with the DVD-VR format on a DVD medium which already has AV data recorded thereon in accordance with the DVD-Video format (for example, for additionally recording on a DVD medium a copy-once program (a program which can be recorded only once), a bilingual program, etc. which is recordable only by the DVD-VR format), the logical format of the DVD media needs to be re-formatted in accordance with the DVD-VR format because of the difference between the formats. However, when the DVD media is re-formatted, the AV data which has been recorded on the DVD media is destroyed and cannot be reproduced.
As described above, when AV data needs to be recorded in accordance with one format on a recording medium which already has AV data recorded thereon in accordance with a different format, it is necessary to give up reproducing the already recorded AV data or to copy the already recorded AV data on a hard disc or the like so as to be recorded later on a different recording medium. The latter has problems of requiring extended time and also requiring a hard disc or the like to which the AV data can be temporarily saved.